Last time, season 7, that only had 7 episodes (all previous seasons had 10), and even one of those was much longer, the season 7 final was just about 80 minutes, whereas a typical episode throughout the series has been from like 52-60m, pretty common for an original cable drama (and obviously no commercial breaks)
and we know coming into season 8 here not only would the offseason be much longer, about 2 years, because they simply had to wait until much longer into the year as they normally have to begin production because they needed EVERY location to be cold and wintery, but there’d only be 6 episodes for the last run.
There was some talk about how much of it would be significantly longer, but again, nobody from the show ever said every episode would be like 90-120 minutes to make up for the shorter episode count. So it’s wound up the first two are actually normal length by GoT standards, then the remaining four being much longer, including episode 3 being the longest episode in the show’s history (by a whole 2 minutes, and remember that includes end credits).
And for episode 3, they shot for almost 60 nights just to get the footage for this episode, it’s supposed to be the longest sustained battle in television or movie history (even longer than the Helms Deep sequence in LOTR: Two Towers).